Apple Lisa 1 - restoration project

[Dan Roganti]

John Honniball wrote:
> David W. Erhart wrote:
>> I've been hoping to get an Apple Lisa for years now.  Recently I had 
>> an Apple Lisa 1 and an Apple Lisa 2 donated to me.
>>
>> I've taken the Lisa 1 apart to examine the damage from the battery acid.
>
> If those are Ni-Cad batteries, it's battery alkali, not
> battery acid.  At least, I think that's correct -- do
> reply if I'm wrong!
>
> Then there's all that green corrosion on the PCB.  See if
> it'll brush off with a dry toothbrush (an old one!) and
> then check for broken PCB traces and/or IC pins. 

There's a lot of corrosion there you have to clean first before you ever 
turn this on. The KOH electrolyte which leaks out is akaline--and it's 
easier to clean at this stage. You can to brush it off with a white 
vinegar(acidic) to neutralize the pH balance, then brush it all off with 
isopropyl alcohol to remove any other residue and blow dry it.
*But*, this has gone way past the leakage stage, the bluish-green 
corrosion indicates that it's already oxidizing--on  the copper traces, 
components, and even solder. This makes it very tough to clean with just 
a tooth brush, as the corrosion actually creeps under the green mask., 
and under the chips where there's plenty of traces. And it becomes very 
hard to resolder anything.
Usually the only method is to:
1. Desolder all the components in that area
    --remove every bit of corrosion with mini wire brush, 320grit 
sandpaper, and/or a dremel wire wheel).
    --if any corrosion remains, it will just grow again and spread.
2. Flux all the feedthrough holes -these will be very stubborn
    --you'll have to flux them several times to make the solder adhere 
properly to avoid further cold solder        
        connections--and then desolder them again.
3. Inspect all the component leads for tension before soldering them back on
    --bend them a little-- as the corrosion creates microscopic cracks.
    --since you have the chips out, use IC sockets in there place.

This may sound like hard work but it's the only recourse and it pays 
off. Don't expect the circuit board to look as pretty as before--you can 
always buy green mask refills--it's recommended. Your computer will be 
happy to work afterwards.

=Dan

-- 
[ Pittsburgh 250th --- http://www2.applegate.org/~ragooman/   ]